Congruence – comparing any 2 objects and know they are the same size or shape.
I developed this entirely solely on prior knowledge. I just thought of what it means to be congruent. You have:
Formal Definition of Congruence: being isometric — roughly, the same size and shape (Wikipedia)
Two-Dimensional: An object having 2 dimensions, the object will have a perimeter and area. The object can be drawn on a flat surface or plane.
This definition is based on my prior knowledge. Example of two-dimentional figures.
Formal definition of Two-Dimensional Shapes: A shape that only has two dimensions (such as width and height) and no thickness.(mathisfun.com)